Double photoionization and transfer ionization of He: Shakeoff theory revisited

The shakeoff theory of Aberg [Phys. Rev. A 2, 1726 (1970) is revisited. With the sudden approximation, we calculate the shakeoff probability when one of the electrons in He is ejected with a finite velocity. This theory is used to examine ratios of cross sections for double to single photoionization and transfer ionization to single electron capture. It is also shown that the momentum distribution of the shakeoff electron provides a means to measure the correlation of the ground state wave function directly.